Blender 2.79b Alembic (abc) export
After having the same problem I figured out a solution.

I installed a different ppa and then went into Synaptic, uninstalled the stock Blender and installed the cutting edge build.  The import and export options are there!  Yay!

Here's the ppa homepage:

https://launchpad.net/~thomas-schiex/+ppa-packages

Pop!_os -- Ubuntu 18.04